A mattress normally includes a coil spring unit defined by a plurality of interconnected coil springs which are united to each other and to upper and lower polygonal frame wires which impart a generally rectangular configuration to the coil spring unit. An upper or top mattress pad and a lower or bottom mattress pad, each formed of multiple layers or plies of materials stitched together, and a like narrow peripheral mattress pad, also formed of multiple plies or layers, are assembled to entirely encapsulate the coil spring unit and form the mattress.
The top, bottom and peripheral mattress pads are each formed as a laminate which might, for example, include a backing material layer, a foam material layer, a fiber material layer and a ticking layer, all stitched together by stitching of a conventional xe2x80x9cquiltxe2x80x9d pattern or design. The materials of the latter layers, the thicknesses thereof, etc. all contribute to such characteristics as softness, breathability, wear, etc. However, irrespective of the particular layers, it is important that the upper mattress pad and the lower mattress pad are manufactured as inexpensively as possible, yet provide the best mattress characteristics possible at the lowest equitable cost over the longest mattress life possible.
A typical conventional mattress corresponding to the mattress just described is disclosed in U.S. Pat. No. 5,317,768 granted on Jun. 7, 1994. The patent discloses a spring component and at least a top surface component formed as a laminate with the outer layer being the ticking or cover fabric, the next inboard layer being a fiber layer, the third layer being a convoluted foam layer, and the innermost fourth layer being a cotton layer with associated stitching holding all four of these layers together to form a quilted multi-ply mattress pad. The thickness of the fiber layer and the thickness of the convoluted foam layer are said to be matters of design choice, though specific examples of weight per square foot of the polyester fiber and the height of the convoluted foam layer are specified as being illustrative. However, it is generally conceded that the best mattresses providing the most comfort are those which include an appreciably thick layer of convoluted foam. However, foam material, particularly latex (natural rubber) foam is extremely expensive and, therefore, appreciably thick convoluted latex foam layers are found most exclusively in higher end, more expensive mattresses. It would be highly desirable to increase the latex foam content in lower end mattresses (less expensive) if costs could be maintained relatively low during the manufacture thereof such that as an end result virtually all qualities of the mattress are appreciably increased at a moderate or low increase in cost at both the wholesale and retail levels.
In keeping with the foregoing, it is a primary object of the present invention to provide as an end product a novel mattress which includes a conventional coil spring unit and at least a top or upper mattress pad formed of multiple plies or layers including at least one fiber layer and one convoluted foam latex layer having conventional peaks and valleys with the valleys being each substantially filled with a multiplicity of relatively inexpensive, small, random sized, foam latex pieces/materials which might otherwise be discarded as scrap, yet possess all of the highly desirable characteristics of a solid latex foam layer. Since the relatively small pieces of foam latex are entrapped in the valleys during lamination, as will be described more specifically herein, the manufacture of such an upper and/or lower multi-ply mattress pad is relatively inexpensive and, thus, can be utilized to enhance all grades of conventional mattresses now being produced, sold and used throughout the world.
In further accordance with the present invention, such relatively small random sized pieces of latex foam material are also preferably sandwiched between two layers of fiber material, such as conventional polyester fiber, to form an upper mattress pad, a lower mattress pad and/or a peripheral mattress pad formed of three plies, namely, a polyester fiber ply or layer, a layer of latex foam pieces and another polyester fiber ply or layer. As thus far described and as opposed to the first laminated mattress pad herein described, the small individual pieces of latex foam (hereinafter termed xe2x80x9clatexxe2x80x9d) would tend to shift or move when in use as part of a mattress, unless otherwise provided for, as is the case of the present invention in which the two polyester layers are stitched together by a conventional quilting machine which not only secures the layers together as a unit, but the stitching confines or limits the movement or xe2x80x9cmigrationxe2x80x9d of the latex when used, for example, as the upper and/or lower mattress pads of a mattress. Thus, conventional stitching of the quilting process not only functions to maintain the two polyester fiber layers (or any other additional layers) united, but the stitching additionally precludes undesired latex migration/shifting which essentially maintains uniform latex thickness and results in a very comfortable yet inexpensive mattress available at low and moderate prices while providing moderate to high quality comfort and softness absent localized xe2x80x9chardxe2x80x9d spots, as might otherwise occur with undesired latex migration.
In keeping with the foregoing, the last described mattress pad is formed by a novel laminating machine of the present invention which provides respective first and second means for rotatably supporting first and second rolls of polyester fiber material with an upper surface of a layer or web of the first roll being fed beneath a trough from which latex/latex pieces are fed. Downstream of the trough a second layer or web of the second roll of polyester fiber material is overlayed upon the pieces of latex at an assembly area during the continuous travel of the polyester fiber layers toward a roll forming or winding station. The thus formed laminate (polyester fiber layer/latex pieces/polyester fiber layer) are then preferably wound into a roll of laminate/laminate roll, the laminate is cut upstream of the roll, and the laminate roll is packaged and shipped to a mattress manufacturer for utilization in the manufacture of a mattress as described earlier herein. An area is provided for storing packaging material, such as a roll of transparent polymeric/copolymeric packaging material, adjacent the roll forming station to use as the packaging material for the laminate roll. Obviously, the diameter of the laminate roll and its length will vary dependent upon the thicknesses of the polyester fiber layers and the amount of latex sandwiched therebetween. No matter the length, width or diameter of the laminate roll, preferably a flying shear or flying cutter severs the laminate normal to the direction of travel in response to automated or manual controls immediately upon completion of the roll packaging operation.
Immediately upon effecting lamination at the lamination or assembly area, the longitudinal edges of the polyester fiber layers are subject to an edge-binding operation which is preferably achieved through spraying a fast drying adhesive therealong which virtually dries instantaneously under normal temperature ranges found in factories, but heaters may be used, as necessary. The adhesive thus sprayed along the longitudinal edges binds all edge-exposed latex pieces to each other and to the polyester fiber layers. Alternatively or additionally, compression edge rollers can be utilized downstream of the adhesive spray applicators, preferably spray guns, to bring the polyester layers into intimate adhesive bonding contact, thereby further assuring that the latex/latex pieces cannot escape the laminate.
In lieu of immediately forming the laminate into a roll, cutting the laminate, packaging the laminate roll and shipping the same to an end user, the laminate may be fed directly into a quilting machine and conventionally quilted or stitched to not only provide unification of the layers and the attendant conventional xe2x80x9cquiltedxe2x80x9d appearance of mattresses, but to also prevent latex xe2x80x9cmigration.xe2x80x9d Conventional quilting machines have multiple programmable stitching heads and in accordance with the present invention, such stitching heads are programmed not only to provide an aesthetic quilt appearance, but to also create essentially a multiplicity of relatively small xe2x80x9cclosedxe2x80x9d pockets between the polyester fiber layers defined by the threads of the stitching with the threads or stitching of each xe2x80x9cpocketxe2x80x9d confining the latex therein and substantially preventing latex migration outwardly of each stitched pocket. The simplest example of the latter is stitching the laminate prior to rolling or immediately upon being unrolled at a mattress fabricator by closely spaced rows of stitching normal and parallel to the direction of travel of the laminate (rolling direction of the laminate roll) to form substantially square or polygonal xe2x80x9cclosedxe2x80x9d pockets, each being relatively xe2x80x9cclosedxe2x80x9d by the stitching associated therewith. Though such xe2x80x9cclosedxe2x80x9d pockets of stitching are desirable, the stitching need not define completely xe2x80x9cclosedxe2x80x9d pockets, but the stitching instead might be configured such as to prevent excessive migration as, for example, closely adjacent parallel sinusoidal stitching either lengthwise or widthwise of the laminate which forms narrow sinusoidal channels which essentially prevent latex migration by the very curved nature thereof and the relatively narrow width of each channel.
The trough which houses the latex preferably includes a tubular polygonal rubber chute carrying at a lower end a latex proportioning gate having a plurality of proportioning openings therein through which pass the latex for deposit upon the upper surface of the polyester fiber layer being conveyed therebeneath. The openings in the gate or plate vary in number, size, shape and orientation depending upon the range of sizes of the particles of the latex being fed therethrough, the amount of latex which is to be deposited per square foot/yard (and thus the eventual height thereof) upon the upper surface of the underlying polyester fiber layer, the speed of production, etc. Gates varying in opening numbers, sizes, shapes and configurations are provided in accordance with the invention for selective utilization to manufacture virtually any and all end product characteristics, such as latex height, density, etc.
The rubber chute or the gate also carries spacers which engage the upper surface of the polyester fiber layer passing therebeneath and assures that this upper surface is spaced at all times a minimum distance from the gate/plate openings. The minimum distance corresponds to the maximum height of the layer of latex which is to be applied to the underlying polyester fiber layer. Since the underlying polyester fiber layer is in continuous motion as it is conveyed toward the assembly/laminating area, its inherent resilience evokes up-and-down movement during the conveyance thereof which, if excessive in an upward direction, will cause the upper surface of the polyester fiber layer to move undesirably closer to the gate openings resulting in the height of the latex being lessened and lessened appreciably beyond that desired. Thus, by maintaining the gate openings at a predetermined minimum distance from the upper surface of the underlying polyester fiber layer during its movement, the thickness/height of the latex is at all times maintained at a uniform desired maximum height which in turn results in a laminate of uniform cross-sectional thickness throughout.
The trough also includes a pair of trough plates, one fixed and another which is adjustable, and between the two trough plates is a vane feed roll or roller which can be rotated at different speeds dependent upon the desired rate of feed of the latex. Lower edges of the trough plates define a transverse slot which can be increased in size by moving the edge of the movable trough plate away from the fixed trough plate and decreased in size by opposite motion for varying the rate of feed of the latex in conjunction with the speed of rotation of the vane feed roll or vane feeder.
The laminating machine also includes a drive mechanism for the take-up roll or roll forming mechanism which is variably adjustable in rotational speed while shafts supporting the rolls of polyester fiber layers or webs are under constant tension of a conventional adjustable brake mechanism. The tension is relatively slight but sufficient to maintain the upper surface of the polyester fiber layer passing beneath the trough relatively horizontally disposed to prevent vertical motion and/or bowing during travel, and thereby assures maximum uniformity of the height of the latex deposited thereupon. Thus, by manually or automatically adjusting the speed of rotation of the shaft upon which the laminate is being wound to form the laminate roll, the amount of latex being deposited upon the upper surface of the underlying polyester fiber layer can be further regulated in conjunction with the earlier mentioned adjustable trough plate, adjustable vane feeder, and different proportioning gates.
The laminating machine can also be utilized to form a multi-ply or laminated mattress pad defined by a convoluted latex foam layer having a relatively flat surface and an opposite surface defining peaks and valleys, latex particles housed within the valleys, and a polyester fiber layer. The latter-described mattress pad is manufactured by the laminating machine in the manner just described with the exception that the downstream roll of polyester fiber material is not utilized, and in lieu thereof a roll of convoluted latex foam is supported upon an associated shaft and is drawn therefrom with its peaks and valleys respectively pointing toward and opening toward the upper surface of the underlying polyester fiber layer. In this fashion as the latex particles deposited upon the upper surface of the lower polyester fiber layer pass beneath and are united with the convoluted latex foam layer, the latex particles are entrapped/encapsulated within the valleys or xe2x80x9cpocketsxe2x80x9d of the convoluted latex foam layer. The laminate thus formed is rolled into a laminate roll and/or stitched by a conventional quilting machine, though the quilt pattern need not provide stitching xe2x80x9cpockets,xe2x80x9d as in the case of the polyester fiber layer/foam latex particles/polyester fiber layer laminate, because the valleys are the xe2x80x9cpocketsxe2x80x9d and prevent latex migration.
With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings.